Police investigating the murder of a man stabbed to death after chasing handbag snatchers in east London have arrested three men.
Sukhwinder Singh, 31, was attacked on Friday as he pursued two men who had mugged a 28-year-old woman in Barking.
Mr Singh died at the Royal London Hospital. A post-mortem test showed he died from a stab wound to the heart.
At 1400 GMT three men were arrested by police acting on intelligence. They are being held in custody in east London.
Police described Mr Singh as a "hero" for his actions.
The woman was walking home from Barking Station at about 1840 GMT when she was attacked from behind by two men who grabbed her handbag.
The bag has not been recovered.
Following the robbery Mr Singh chased the suspects for about 60 yards along Victoria Road into Uphall Road, where it is believed that an altercation took place and he was stabbed.
A Metropolitan Police spokesman said they now believed more than two suspects were involved in the killing.
Det Ch Insp Stephen Clayman said: "We need to hear from anybody who witnessed the initial robbery, the actual stabbing and anyone who may have seen suspects running away from the Uphall Road area.
"I wish to encourage members of the public to come forward and speak to police - no matter how insignificant they may feel their information is."
He added: "If they have fears regarding speaking to police, I assure them that we can allay those fears."
Mr Singh was an Indian national who had lived in the UK for about 10 years.
According to the Met, he had cousins in Barking but his family lived in India.
Earlier on Wednesday police released a CCTV image of the handbag believed to have been stolen.